Research On New Sensor Optimization Design And Algorithm Based On ECT

The Electrical Capacitance Tomography(ECT)has the advantages of non-invasiveness,safety,fast response,convenient installation,and low cost,which makes this technology a potential for development in the visual inspection of industrial processes.technology.In order to analyze the capacitance tomography system in depth,the main work of this thesis includes the following aspects:1.Explain the basic principles of ECT technology,and mathematical models for forward and inverse problems.Design a 12-electrode ECT system sensor.This paper studies some traditional image reconstruction algorithms,introduces the imaging principle of the algorithm,analyzes its advantages and disadvantages,and evaluates the reconstruction effect by calculating relevant evaluation indicators.2.In order to reduce the noise value of capacitance measurement caused by the coupling capacitance between adjacent plates of ECT sensor,a differential electrode sensor system is designed and the parameters of differential electrode and measuring electrode distance are optimized.The experimental system uses FPGA direct digital frequency generation module to generate digital quantity.The sinusoidal excitation signal is converted into a positive and negative alternating current signal by D/A to excite the measuring electrode and the differential electrode,respectively.The sensor sensitivity is best when the ratio of the distance between the differential electrode and the measuring electrode to the midpoint of the pipe is about 1:1.2.3.The measuring electrodes of traditional ECT sensor systems are fixed on the pipe wall,the distance between the measuring electrode and the center of the pipe is fixed,and electrode-to-gap ratio(EGR)is also fixed.A new sensor system with adjustable duty cycle is proposed,which is more convenient and quick in practical industrial applications To get a better reconstructed image.In order to eliminate the interference capacitance between the plates,a sensor system with a differential electrode is designed.The differential electrode is installed between the measurement electrode and the shield,and the differential electrode and the measurement electrodechange synchronously.4.Firstly,the double conjugate gradient algorithm is introduced into the capacitance tomography technology,and the simulation image reconstruction resolution through experimental design is high.In order to obtain a better imaging effect and shorten the imaging time,the algorithm is improved by combining the dual conjugate gradient and Tikhonov regularization algorithm,and then compared with the traditional iterative algorithm.5.The new optimized sensor system is used in combination with the improved BICG algorithm to obtain better imaging results through simulation experiments,which makes it widely used.